The present invention relates to a magnetic recording and reproducing system. More particularly, the present invention relates to a magnetic recording system for recording a digital signal in the form of a two dimensional plane on a magnetic recording medium such as a magnetic tape, a magnetic disc and so on. The present invention also relates to a magnetic recording medium on which a digital signal has been recorded by the above recording system, and to a reproducing system for the recorded information on the magnetic recording medium.
Conventionally, magnetically recorded information, recorded for instance on a magnetic tape, a magnetic disc, or a magnetic sheet, is read out by a magnetic head which has a magnetic core with a thin gap and a coil wound on said core. A magnetic head operates on the principle that the relative movement of the head to the recording medium generates electromotive force on the coil according to the recorded information.
However, that conventional magnetic head has the disadvantage that the recording density on a recording medium can not be so high. It is said that a conventional magnetic head needs a recording track wider than 30 .mu.m.
In order to solve the above problem, one of the solutions is an optical head which reads out magnetically recorded information using an optic-magnetic effect or the Faraday effect. According to that optical head, a soft magnetic film which has a magnetically soft nature contacts with a recording medium which records information magnetically, and the vertical component of the magnetically recorded information on the recording medium is copied on that soft magnetic film. The information on the soft magnetic film is read out optically using the Faraday effect in which an optical beam is subject to the rotation of the polarization plane according to the magnetic direction of a magnetic domain of that soft magnetic film. As the Faraday effect is used, an optical polarizer and an optical analyzer are usually used to detect the optical rotation of a polarized optical beam.
Japanese Patent Laid-Open No. 100713/79 discloses a system for recording a figure or a letter as it is on a magnetic recording medium, and for reproducing it therefrom with an optical technique. This prior system records the data on the recording medium such that a small magnetic pole is moved in accordance with the shape of the data pattern to be recorded. However, this prior system has the disadvantage that its structure becomes very complicated because of the necessity of the relative movement of the small magnetic pole or the recording medium to the data pattern to be recorded.